Test Description

WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

2: When the system is operating correctly, the HO2S 1 voltage should toggle above and below the bias voltage. You may need to operate the vehicle within the Freeze Frame conditions and Conditions for Setting the DTC in order to duplicate the malfunction that was detected by the ECM.
4: The specified value is what is measured on a correctly operating system.

DTC P1171

Step	Action	Values	Yes	No
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views
1	Did you perform the Diagnostic System Check - Vehicle?	-	Go to Step 2	Go to Diagnostic System Check - Vehicle
2	Operate the engine at normal operating temperature. Operate the engine above 1,200 RPM for 2 minutes. Observe the heated oxygen sensor (HO2S) 1 voltage parameter with a scan tool. Does the scan tool indicate that the heated oxygen sensor (HO2S) 1 voltage is less than the specified value?	300 mV	Go to Step 4	Go to Step 3
3	Observe the Freeze Frame/Failure Records for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition?	-	Go to Step 4	Go to Diagnostic Aids In This Test
4	Turn OFF the ignition. Disconnect the HO2S sensor. Turn ON the ignition, with the engine OFF. Measure the voltage from the high signal circuit of the HO2S 1 on the vehicle harness side to a good ground with a DMM. Does the voltage measure within the specified value?	350-550 mV	Go to Step 6	Go to Step 5
5	Test the HO2S 1 high signal circuit for a short to ground or a short to the HO2S 1 low signal circuit. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	-	Go to Step 11	Go to Step 8
6	The HO2S 1 is detecting a lean condition or may be contaminated. Inspect for the following conditions: HO2S connector water intrusion Silicon-contaminated HO2S An exhaust leak between the HO2S 1 and the engine. Refer to Exhaust Leakage . Vacuum leaks Incorrect fuel pressure-Refer to Fuel System Diagnosis . Lean fuel injectors-Refer to Fuel Injector Diagnosis (w/J39021 or w/Tech 2) or Fuel Injector Diagnosis (w/CH47976) . Repair any of the above or similar engine conditions as necessary. Did you find and correct the condition?	-	Go to Step 11	Go to Step 7
7	Inspect for poor connections at the harness connector of the HO2S 1 sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	-	Go to Step 11	Go to Step 9
8	Inspect for poor connections at the harness connector of the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	-	Go to Step 11	Go to Step 10
9	IMPORTANT: Before replacing the HO2S, determine and remove any source of contamination. Replace the HO2S 1. Refer to Heated Oxygen Sensor 1 Replacement .Did you complete the replacement?	-	Go to Step 11	-
10	Replace the ECM. Refer to Control Module References for replacement, setup, and programming. Did you complete the repair?	-	Go to Step 11	-
11	Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition?	-	Go to Step 2	Go to Step 12
12	Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?	-	Go to Diagnostic Trouble Code (DTC) List - Vehicle	System OK